1. Technical Field
The present invention relates to a method and an apparatus for producing a three-dimensionally shaped object and a three-dimensionally shaped object.
2. Related Art
For example, JP-A-6-218712 discloses a method of shaping a three-dimensional object while solidifying a powder with a liquid binder. In this method, the three-dimensional object is formed by repeating the sequence of the following operations. First, a powder is spread to form a powder layer having a uniform thickness, and a liquid binder is ejected onto a desired portion of the powder layer to bind the powder particles. Consequently, only the powder particles in the portion of the powder layer onto which the liquid binder has been ejected are bound to form a thin plate-like member (hereinafter referred to as the “cross-section member”). On this powder layer, then, a further thin powder layer is formed, and a liquid binder (curable ink) is ejected onto a desired portion of this further powder layer. Consequently, another cross-section member is formed in the portion of the further powder layer onto which the liquid binder has been ejected. At this time, the liquid binder ejected onto the powder layer penetrates into the previously formed cross-section member, so that the newly formed cross-section member is bound to the previously formed cross-section member. By repeating the sequence of these operations, thin plate-like cross-section members are formed one on top of another, thus forming a three-dimensional object.
This technique allows an object to be easily shaped by simply binding powder particles only using data of the three-dimensional shape of the object to be shaped. Also, this technique does not require preparing a molding die in advance, and accordingly enables fast inexpensive shaping of three-dimensional objects. Furthermore, since the thin plate-like cross-section members are formed one by one, even a complicated object having an internal structure can be formed in one body without combining a plurality of components.
In the known method, however, the same amount of a liquid binder is applied to each powder layer even if the thickness of the powder layers has variations. This amount of the liquid binder may be excessively small or excessively large depending on the portion of the powder layer. This can cause powder particles in some portions to fail to bind to each other. Consequently, the mechanical strength of the resulting three-dimensionally shaped object is reduced.